Green’s Dictionary of Slang

1. (Aus.) the human head.

1923		Australasian (Melbourne) 23 June 49/4: ‘What would you do if you had to live with and be beholden to a man whose very presence in the room made you squirm?’ [...] ‘Do? Why I’d—I’d dong him on the cruet!’.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxiii 4/4: cruet: Head.
1977		(con. 1941) R. Beilby Gunner 139: ‘Where did he get it?’ ‘Through the cruet.’.

2. (Aus.) as the cruets, the testicles.

2012		Big Footy 24 July 🌐 Knowing our luck it'll be upgraded to him trying to knee the other guy in the cruets.
2014		Sun. Mail (Brisbane) 26 Jan. 🌐 When legendary broadcasters H.G. Nelson and Roy Slaven referred to a sportsman being hit in the cruets or the wedding tackle, you didn't need a medical degree to work out what sort of pain the poor fellow would be enduring.